Class differences have always existed whether it is by tribe, village, profession, financial status or two people who have their own little imaginary clique going.
Forget trying to make everyone friendly (although that would be a start) and teach kids that sometimes it's great to be different. You can't go places with limits tied around your neck. Schools should make every kid feel needed somewhere, especially those who can't quite make it on their own.

If a weapon is outside of the safe, then it should be on your body or in your hands, at the very least within your reach.
Children have NEVER understood "Don't touch". It is against their nature of exploration in order to learn. That's why they have parents.